MCB advice, B-type to C-type

[gaz_moose]

My household consumer unit is in the garage. A good while ago I had an electrician install me a 32amp commando socket about 1 meter away from the consumer unit to supply my transformer based tig welder. I was not very clued up on electric at the time so just explained what I was after and left him to it.

I mainly use my tig on the lower settings and it sometimes trips the circuit breaker. today I tried to use the higher settings and I found I would trip the breaker about every 10mm of weld.

looking at the breaker I can see that he has fitted a B-type MCB, my question is if I fit a C-type breaker will it cure the constant tripping? I would have thought it would trip when I tried to strike an arc due to the sudden rush and not after a roughly a minute.

 

[123hotchef]

yes a C curve would probably not trip I need to change mine too

 

[Barlidge]

I have a similar setup but mine only trips when powering the welder on, after that its fine.

 

[WorkshopChris]

I would have thought it would trip when I tried to strike an arc due to the sudden rush and not after a roughly a minute.

That,s what normally happens, what rating of mcb do you have fitted at the moment?

 

[brightspark]

My household consumer unit is in the garage. A good while ago I had an electrician install me a 32amp commando socket about 1 meter away from the consumer unit to supply my transformer based tig welder. I was not very clued up on electric at the time so just explained what I was after and left him to it.

I mainly use my tig on the lower settings and it sometimes trips the circuit breaker. today I tried to use the higher settings and I found I would trip the breaker about every 10mm of weld.

looking at the breaker I can see that he has fitted a B-type MCB, my question is if I fit a C-type breaker will it cure the constant tripping? I would have thought it would trip when I tried to strike an arc due to the sudden rush and not after a roughly a minute.

what size breaker did he fit . amperage

 

[123hotchef]

I have a similar problem with my outdoor heater when turning it on it trips the 16amp breaker and will trip it for 2 or 3 times before actually staying on. It is a 2.5mm2 radial feeding the lamp and a strip light the breaker is fine with the light alone. @brightspark would a c curve fix my problem?

 

[Jim Davey]

As Brightspark says, we need to know the amperage of the breaker the electrician installed, but also I'd like to see a picture of the rating plate data off your set. It will help us to know if the set actually draws more than your 32 amp socket provides for.

 

[WorkshopChris]

Am sure brightspark will be along soon but there are lots of factors to consider its not just a simple swap in most cases, as it can affect cable ratings and earthing requirement. I normally fit a type c20 on nearly everything with radials on 4 or 6mm singles in conduit. Except 16a socket outlets they normally get c10 on 4mm Often rcbo's in place of mcb's but that sort of thing is harder to find for domestic boards.

 

[gaz_moose]

Sorry for the delay, got side tracked by the pikeys trying to nick my caravan off my driveway!!
it says 61/B32 on the breaker.

its a 1993 Arc-Tec made by UK welding systems, it has no data plate on the back and I don't have the manual.

this is the thread I posted when I first got the machine which shows what the front is like.
http://www.mig-welding.co.uk/forum/threads/a-little-help-please-from-those-that-know-electrics.8054/

this guy bough the 200 amp mig welder version which does have a data plate. so I assumed mine would be around the same kind of figures stated on his data plate.
http://www.mig-welding.co.uk/forum/threads/arc-tec-200a-single-phase-mig.13778/

 

[gaz_moose]

is there a way I can measure what it is drawing from the supply?

 

[brightspark]

is there a way I can measure what it is drawing from the supply?

yes a clamp on ammeter preferably with inrush current hold

 

[gaz_moose]

so I can put a clamp meter on the main power cable to the machine, 'do a weld' , trip the MCB and it will tell me what amps it pulled when it blew? guess I should set the machine to max and thick ally.

its just occurred to me that ive welded on higher settings before when using it in DC mode to weld steel. I guess it must demand more when welding ally.

 

[brightspark]

if its single phase u need to put the clamp over just the live feed input cable only . run it at full power and take the reading

 

[gaz_moose]

so best to pop the side panel off and put it on the brown wire. as the main infeed cable is 3 core.

or can I just clamp the 3 core?

what does the 61 on my circuit breaker mean? it says 61/B32 I get that, B because its a B type breaker 32 is the amps.

the guy who put it in has wired it with what look like 2 lengths of 2.5 twin and earth. google suggests that it is only rated to 24 amps should I get it redone in 4mm??

 

[dannyp]

. I normally fit a type c20 on nearly everything with radials on 4 or 6mm singles in conduit. Except 16a socket outlets they normally get c10 on 4mm Often rcbo's in place of mcb's but that sort of thing is harder to find for domestic boards.

10A breacker on 16A sockets that would wind me right up

 

[brightspark]

so best to pop the side panel off and put it on the brown wire. as the main infeed cable is 3 core.

or can I just clamp the 3 core?

what does the 61 on my circuit breaker mean? it says 61/B32 I get that, B because its a B type breaker 32 is the amps.

the guy who put it in has wired it with what look like 2 lengths of 2.5 twin and earth. google suggests that it is only rated to 24 amps should I get it redone in 4mm??

do u mean 2 lengths in parallel that would make 5mm just clamp the brown feed cable it wontread if u clamp all 3

 

[gaz_moose]

yes 2 lengths in parallel.

I will have to get a new clamp meter as mine seemed to vanish.

 

[WorkshopChris]

10A breacker on 16A sockets that would wind me right up

That's the difference with a C rated breaker. When you look at at the curve you need to be pushing then very hard to trip one.
Have stuff that will run all day on a C10 but takes out a B20 every now and again. On two occasions its saved small compressor motors as they have tripped for a fault before the 13a fuse blown.
If it needs more then it normally gets moved up to a 32a plug. Or occasionally swapped for a C16.
Never had anything on a 13a plug that trips a C10 apart from heaters. (constant load)
It still gives you fault protection without problems or start up in rush tripping.
Most of the stuff we use is fairly static only getting moved around occasionally.

 

[barracuda816]

As long as your zs values are within spec for the type and value of the breaker you dont need to derate. ie if the zs value is <0.72ohm you can still replace a b32 with a C32 to a 2.5mm2 ring or a 4mm2 radial.

 

[dannyp]

they still wind me up on site repairs tho. when you've only got a 16A outlet, you really want a 32A but it's possible with 16A just to find out it's actualy a 10A

become highly tuned into not quite tripping various breackers with the inverter stick set